| abstract |
Synthetic processes are provided wherein mixed backbone oligomeric compounds are prepared having at least one phosphodiester intemucleoside linkage in addition to one or more phosphorothioate, phosphoramidate and boranophosphate internucleoside linkages. Novel H-phosphonate intermediates are also disclosed that are useful in the synthetic processes. The synthetic processes use a novel oxidation step to oxidize H-phosphonate internuleoside linkages to phosphodiester internuleoside linkages without degradation of adjacent phosphorothioate, phosphoramidate and boranophosphate internucleoside linkages. Also provided are synthetic intermediates useful in such processes. |